Like many firm supporters of Bernie Sanders these days,one of my first activities after rolling out of bed is to Google Bernie’s name and click the “news” tab. I woke up today to the top story from CNN titled “Poll: Hillary Clinton’s lead over Bernie Sanders Grows.” Having become used to this type of treatment of Bernie from the corporate media, I clicked it to read and examine whether the headline actually matches the content. My first impression was that this “lead growth” isn’t really very conclusive. Then I looked more closely at the data, and I realized something I could hardly believe – they skewed the results.
The gist of the story was that Clinton’s lead over Sanders, which had been 37% to 27% in this poll, had grown to 42% to 24%. However, the story went on, when Biden is not included on the ballot, that lead balloons to a whopping 57% to 28%. Initially I was willing to take these figures at face value because they comported with the facts that I believe to be true at the moment. The CNN poll has a margin of +/- 5% for this particular question, and both Hillary’s and Bernie’s numbers were within those margin. Secondly, other polls had demonstrated that Joe Biden’s support has significant overlap with Hillary Clinton’s and that his candidacy siphons far more votes away from Clinton than Sanders.
However, something just didn’t sit right with me. Since the previous CNN poll had been taken, Bernie Sanders didn’t have a noteworthy gaffe, and Hillary Clinton didn’t leave a particularly positive impression either at an interview or at a town hall meeting. In fact, most of the news coverage has been on the Republicans because, thanks to our illustrious DNC Chair, the Democrats are receiving a fraction of the media attention due to a limited number of debates. That’s why I decided to delve into the details of the poll, the numbers behind the numbers, and compare the old poll released September 10th and this new one with Clinton’s allegedly increased lead.
Like any respected poll, CNN lays out its methodology to tell you who they interviewed, how many of each group (Democrats, Republicans, independents and so on) and the margins of error. Both polls are prefaced by this statement. Read this one carefully because it contains the key to understanding what CNN did here.
“Crosstabs on the following pages only include results for subgroups with enough unweighted cases to produce a sampling error of +/- 8.5 percentage points or less. Some subgroups represent too small a share of the national population to produce crosstabs with an acceptable sampling error. Interviews were conducted among these subgroups, but results for groups with a sampling error larger than +/-8.5 percentage points are not displayed and instead are denoted with “N/A”.
For the uninitiated, “crosstabs” refer to subgroups within a poll. So let’s say you want to check how many black democrats support Hillary, or how many college graduates like Bernie, or how Martin O’Malley is doing with voters with a household income of over $50,000, you would refer to the various crosstabs for race, education level and income, respectively. In the passage that I have underlined, CNN is telling you that if certain crosstabs are so small in their sample size that they couldn’t possibly give you a margin of error, then they will not even bother to give you the numbers among the cross tabs because the numbers would be utterly useless and would just indicate “N/A” short for “not applicable”, or possibly in this case “not available.”
There is one other common cross tab that polls look at – age. CNN’s new poll is LOADED with older voters more than any other age group. We know this because only the 50-64 and 65+ age groups was statistically large enough to give an accurate sample, whereas all the other ones are denoted with “N/A” meaning their sample size was too small. Even when they combined all the subgroups into two, those over age 50 and those under age 50, the under 50 vote was STILL too small to give a statistically significant sample. In other words, the number of over voters over the age 50 was greater than those under 50.
When you factor in exit polling data that shows voters age 30-44 have outnumbered senior citizen voters in each of the last three presidential elections, when you factor in that the last two have seen voters ages 18-30 leapfrog 65+ voters, you have to ask yourself how representative this sample is that so heavily concentrates on the oldest segment of our population in far larger proportions than what the last three elections would justify. That undersampling becomes even harder to justify when you consider the fact that this is only a Democratic primary, an electorate which we know from other respected polling skews even younger than the general electorate.
Loading the poll with seniors is precisely what gives Clinton such an edge. We have reported that age is a significant factor in the Democratic primary based on previous polling data. For instance the recent CBS/New York times poll showed Clinton in the lead over Sanders, but when crosstabbed with age, it showed Sanders at 40% support among voters age 18-49, essentially tied with Clinton at 39%. Meanwhile, Clinton had a commanding lead among voters over the age of 50, which showed that while Clinton dropped in the previous months in support, Sanders picked up only a third of those voters, while two thirds of them migrated to Joe Biden. It is no surprise then, that in a sample of voters who skew so heavily towards the older demographics that Hillary Clinton would be doing well, and Joe Biden would be competitively running just two percent behind Sanders.
Whether CNN did this because they are in the tank for the Clinton people, or whether they are biased in favor of reporting on a more exciting horserace where each candidate takes turns having good and bad news at polling, or for any other far less siniste reason, it makes no difference that their reporting leaves a great deal to be desired. If I was able to figure that out in less than an hour of analyzing this poll, any journalist good enough to get hired by CNN should have caught it as well. Nevertheless, that didn’t happen and we spent an entire news cycle reading about how well Hillary is doing among voters over 50 masquerading as the entire Democratic electorate. Reporting which lacks credibility does not do any favors to a cable news industry that is already dying because of its failure to get traction with younger viewers. Be very careful what you read, (that goes for this piece too) and always check what’s behind the headline. Last but definitely not least, if you are a Bernie supporter, work to increase turnout of millenial age voters and Bernie will win the nomination, and subsequently the election.